Human Mental Abilities
Lecture 1
Leonardo Gabales
Griffith-Taylor 310
9351 7479
leong@psych.usyd.edu.au
1
Human Mental Abilities

Intelligence or cognitive abilities…

A central aspect of Individual Differences or
Differential Psychology




Abilities
Personality
Preferences, beliefs, & tendencies, etc…
Everyone is in certain respects…
(a) like all other people,
(b) like some other people,
(c) like no other people.
2
Differential Psychology

As a scientific discipline is concerned with…



Description,
Explanation, &
Prediction
…of reliable individual variation in human behaviour
(e.g., ability test scores, responses on
questionnaires, performance) rather than aggregated
group differences per se
3
Implicit Notions of Intelligence…
Thinks about
things logically
Has a good store
of information
Has good
problem-solving
skills
Has a good
memory
Has good
reasoning skills
Is creative
Processes
information
quickly
An intelligent
person …
Learns new
things quickly
Is highly
educated
Others …
4
What is intelligence?!


Differences between ‘lay’ (or naïve) & scientific
approaches to understanding intelligence…
In every day life we observe, try to understand, &
predict the behaviour of others

Based on… systems of culturally based beliefs &
subjective evaluations of human behaviour & its
potential causes

Implicit assumptions about causes of behaviour

Implicit assumptions about distributions
5
‘Lay’ vs Scientific Approaches

Judgments based on ‘lay’ understandings of
intelligence (& other psychological concepts) are
useful in our day-to-day lives… but, are:




Imprecise
Inconsistent
Not useful as psychological (scientific) theories
Good news - bad news

Good:


similar terminologies
Bad:

similar terminologies
6
What is intelligence?!


“Intelligence is a word with so many meanings that
finally it has none” Charles Spearman (1927)
“Intelligence is what the tests test” e.g. Boring (1951)
Because …
Person ‘X’ is
intelligent
Because …
Person ‘X’
performs well on
intelligence tests
7
An “Intelligence” Test




What is the capital of Turkmenistan?
 Ashgabat
Who wrote “At the Mountains of Madness?”
 H. P. Lovecraft
What is the most number of Oscars won by a film?
Name the film/films.
 11: LotR: Return of the King, Titanic, and Ben-Hur
What is longest streak of consecutive NBA titles?
Name the team.
 8: Boston Celtics
8
Intelligence is what
intelligence test test?!

As you can see from our “intelligence” test
there are big problems with this…



Doesn’t help our understanding of what
intelligence actually is
Allows us to define intelligence as almost anything
Problems with reliability and validity (which, we will
come back to later)
9
Cognitive Abilities

There is a need to make a distinction between
cognitive abilities & task performance
J. B. CARROLL (1993)


Cognitive tasks: ‘Any task in which correct or
appropriate processing of mental information is critical to
successful performance’
Cognitive ability: ‘Any ability that concerns some class
of cognitive tasks, so defined’
10
Intelligence as a construct

Two levels:

Manifest variables – observable…


What we can see (e.g., behaviour, test scores,
responses)
Latent variables – unobservable…

What we infer – constructs (e.g., abilities, traits,
states)
Task 1
Cognitive
Ability
Task 2
Task 3
11
Constructs

Theoretical (or hypothetical) terms which cannot be
directly observed, but are assumed to exist because they
give rise to measurable phenomena



Constructs are not discovered, but constructed
Description (& explanation) of behavioural &
performance data
Basis for prediction of behaviour

Constructs are defined by:
 Empirical indicators
 Relationships to other constructs
 Network of constructs (nomological network) = theory

THEREFORE: Theory & measurement are inextricably linked12
Psychological Assessment

Psychometric tests do not provide a perfect index of cognitive ability

Behaviour (e.g., test performance) is often viewed as a function of
person (e.g., cognitive ability) & situation (test context) factors
Performance in
Situation X
?
Behaviour in
Situation Y
?
‘Manifest’ or
observable
?
‘Latent’ or
unobservable
Cognitive
Factors
Non-Cognitive
Factors
13
A (Brief) History: Galton

Francis GALTON [1822-1911] – the
founder of modern individual differences
psychology:


Developed a variety of (psychophysical)
measuring instruments (e.g., Galton whistle)
Developed the first anthropometric laboratory

Data on a large number of psychological & physical
measures (across a sample size of thousands) was obtained
14
Galton

Drew attention to statistical distributions (esp. the
Gaussian normal curve) that might describe many
physical & psychological characteristics

Developed regression techniques leading to the
construction of the coefficient of correlation

Pioneering research in behaviour genetics: work on
regression techniques and the normal curve were
combined - the concept of "regression to the mean"
15
Galton
16
Galton

Hereditary Genius (1869) claimed that
intellectual genius tended to run in families:


“I have no patience with the hypothesis that the sole
agencies creating differences between men are
steady application and effort”
Inquiries into the Human Faculty … (1883) laid
the foundations for a theory of cognitive abilities

Claimed tests should be used to identify mental
strengths & weaknesses
17
Galton

Galton’s efforts to measure intelligence were
ultimately a failure:

Tests measured: body length, reaction time, visual
acuity & body breadth - only RT could be regarded as
anything like a cognitive ability

Failure was due to the variables selected

“All the information that reaches us passes through the
avenue of the senses; the more perceptive the senses, the
larger the field on which our intelligence can act”
18
A (Brief) History: McKeen
Cattell

James McKEEN CATTELL [1860-1944]

Main figure behind the mental testing
movement during the 1890s - credited with
coining the term ‘mental test’

Developed an extensive test battery administered to many college students included tests of RT, sensory discrimination,
word associations, picture-naming speed &
others
19
A (Brief) History: Wissler

Clark WISSLER [1870-1947]


Attempted to associate results from Y tests with
‘other’ estimates of intelligence – reasoned that Y
test scores should relate to academic performance
Conducted the first extensive application of the
correlational method (1901)

Found disappointingly low correlations between Y test
scores (including RT) & college grades
20
A (Brief) History: Spearman

Charles SPEARMAN [1863-1945]

One of the first to use correlation coefficients
in large-scale empirical research

Developed the statistical method of factor
analysis

Proposed the g-factor theory of intelligence
that has supporters to this day
21
A (Brief) History: Binet

Alfred BINET [1857-1911]


Shifted emphasis to examine ‘higher mental
processes’ - designing tests to measure
‘complex’ abilities (The Stanford-Binet IV is
still used today)
An attempt to ensure ‘defective children
receive the benefits of tuition’ - no clear
definition regarding mental retardation developed ‘mental age’ IQ
22
A (Brief) History: Binet



Tasks varied widely – although most relied on
understanding language or the ability to
reason with verbal or non-verbal material
The scale & revisions formed the basis for the
development of intelligence scales (both
individual & group) in a number of countries &
languages
Development & refinement of Y tests was
accompanied by evolution of statistical
techniques
23
Defining Y Tests

A measure of a sample of behaviour

Since one sample is likely to provide an
unreliable estimate - tests provide several
samples of the behaviour of interest (i.e.,
items)

The final measure is some function of an
individual's response (i.e., appropriately
marked items)
24
Test Items

To provide a meaningful estimate of the
behaviour of interest, items should be
based on:

Some meaningful theory about the nature of
cognition (cognitive tests)

Drawn from a well-defined domain
(achievement tests)
25
Uses of Y Tests

“Mental tests are psychology’s
greatest contribution to society”
(Anastasi & Urbina, 1999)

Tests are employed in many areas,
including:
Education
 Personnel selection
 Clinical assessment

26
Criticisms of Y Tests

During the 1970s, mental testing came
under attack by social scientists

The main criticisms concerned:


Bias in psychological test
The static nature of intelligence test scores
27
Bias in Y Testing
Significant differences between groups:






Racial differences - black vs. white
Gender differences - male vs. female
Age differences - young vs. old
Socio-economic differences - rich vs. poor
CLAIM: differences b/w groups are not
real, BUT … a consequence of bias in
mental tests
28
Bias in Y Testing

A large number of studies examining the
issue of bias were conducted during the
1980s

It is now generally accepted that:

Most tests when used appropriately contain little
bias


Psychometric tests don’t hurt people - people hurt people
Other assessments proposed as replacements for
psychological tests often demonstrate more bias 29
Static Nature of Y Test Scores

Psychometric tests provide only a single
score - the final outcome of a problem
solving process

This score is the sum of coded answers to
test items & places an individual relative to
others taking the same test
30
Static Nature of Y Test Scores

This score has nothing to say about:




The way a person thinks
The steps underlying the solution process
The nature of cognitive processing employed
This line of criticism has prompted:


New ways of testing intelligence (e.g., adaptive
testing, dynamic assessments)
Theory (rather than operationally) based
psychometric test paradigms
31
Summary

Intelligence as a latent construct…

The distinction between cognitive abilities & cognitive task
performance

Theory development is linked to greater
sophistication in assessment/measurement

Psychometric tests contain little bias when used
appropriately & represent better options in
assessment than alternatives
32
Think about how stupid the average person is;
now realise half of them are dumber than
that.
(George Carlin)
33